The present invention relates to a method for forming a contact hole of a semiconductor device. More particularly, the present invention relates to a method for forming a contact hole using a spacer patterning technology (SPT).
Recently, as semiconductor devices become smaller and highly integrated, the whole chip area is increased in proportion to an increase in memory capacity. However, an area of a cell region in the semiconductor device, which contains patterns, is practically decreased.
Thus, in order to form a large number of patterns in a limited cell region, a pitch size of patterns, for example, a critical dimension (CD) of a pattern or distance between two adjacent patterns becomes reduced.
In addition, such fine patterns are formed via a photolithography process.
In the photolithography process, a photoresist film is coated over a substrate. An exposure process is performed on the photoresist film with an exposure mask where fine patterns are defined, by a laser light source, e.g., i-line (365 nm), KrF (248 nm), ArF (193 nm) or F2 (153 nm). A development process is then carried out to form a photoresist film pattern.
However, as a design rule of semiconductor devices is decreased, the pitch size of patterns which is realized in the semiconductor devices becomes reduced. Since the maximum resolution of a photolithography apparatus is preset, it is difficult to form patterns that are finer than the maximum resolution of the apparatus. In particularly, in order to form patterns having a pitch finer than the maximum resolution, a masking process is performed a plurality of times. This process complicates the overall process for forming a fine pattern. For example, each time a masking process is performed, there is a chance that a misalignment could occur so a repeated masking process correspondingly increases the likelihood of misalignment. A repeated masking process also raises the chance of a semiconductor device being contaminated due to contact with a mask.
Accordingly, there is a demand for a method for forming a fine pattern such as a contact hole with simplified process steps.